update package freetype
update package libpng
package bullet: fix update macro
Merge branch 'master' of github.com:mxe/mxe
package pthreads-w32: fix for shared build

- Only patch header files to force static build when we are actually
  running a static build.
- Install DLL into bin and stub .a into lib for shared.
Package boost: Enable shared builds
Package lcms1: Enable shared builds
Package gnutls: Fix export for shared build
package hdf5: remove libtool workaround (actually a pthreads build issue)
doc update: alphabetise the list of packages
package curl: install prefixed curl-config
package xmlrpc-c: use prefixed curl-config and build test program